(Tadoussac) The icy water takes your breath away as soon as you enter. Despite the diving suit, which feels like a second skin, its 4°C temperature is clearly felt. Anne-Marie Asselin seems in her element. Floating on the surface in her apple green suit, equipped with a mask and snorkel, the marine biologist scans the depths of the St. Lawrence.
Suddenly, she takes a deep breath and, with a stroke of her flipper, dives to a depth of about ten meters, helped by the weights she wears at her waist. She rummages for a few moments at the bottom of the water, stirring up a small cloud of mud, then comes back to the surface and brandishes, all smiles, the two sea urchins she has recovered.
These small invertebrates will then be brought back onto the sailboat Let’s gowhich accompanies the Blue Expedition, before being sent to a laboratory to measure the quantity of microplastics they contain.
Mapping plastic pollution
The expedition is not only interested in sea urchins, far from it. Other invertebrates, but also surface water and sediments at the bottom of the river, will also be collected and analyzed.
The team repeated the operation in different locations, for 18 days, in the Saguenay River and the St. Lawrence Estuary, between La Malbaie and Les Escoumins.
“This allows us to draw up a portrait of the microplastic pollution of the river, and to go back a few years by collecting sediments, to see how it has evolved over time,” explains Miguel Felismino, a doctoral student in biology at McGill University.
The team also collected waste from the banks, which had washed up there after drifting with the currents. They carefully listed and classified it into no fewer than 156 categories, in an attempt to trace its origin.
Because the goal of the Blue Expedition is to map waste and microplastics, but also to understand how they got there.
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The ubiquitous plastic
This expedition is the second carried out by the Organisation Bleue, an organization founded by Anne-Marie Asselin. The first, in 2022, focused on plastic pollution in the Gulf of St. Lawrence; this year, the team is focusing instead on the maritime estuary of the river, a little further upstream.
Read our text on the first Blue Expedition
“What we found during these two expeditions is that plastic is truly omnipresent, wherever we go,” says Anne-Marie Asselin with a sigh. “There is no place that is free of it. In the air, in the water, on the ground. It’s everywhere.”
“And contrary to what one might think, the closer you go to the Gulf, the more the density of plastic increases,” explains Laurence Martel, project coordinator at Organisation Bleue. “While in the collective imagination, we tend to think that the areas around large urban centres are the most polluted – like near Montreal, Quebec City or Trois-Rivières. This clearly demonstrates the impact of marine currents in the river,” adds the woman who is also a geographer specializing in hydrology.
The waste they found in greatest number were, by far, cigarette butts, followed by plastic bottles and bags, then single-use utensils.
As for microplastics, what we mainly find are synthetic microfibers from washing clothes.
And it was on small wild islands, far from any human presence, that the expedition discovered the largest dumps: the waste that had drifted there had accumulated there for years.
Better understanding for better prevention
A public database was launched in 2019 by the Blue Organization to identify plastic waste polluting waterways and oceans in Eastern Canada. Many organizations contribute to it regularly. Another database, which will this time assess the presence of microplastics, should also soon see the light of day.
Ultimately, this research could prompt policymakers to take action to stem the problem.
The federal government wants to protect 30% of the oceans by 2030, but much of the plastic that pollutes them comes from rivers and streams. It is hoped that this research will allow it to make more informed decisions.
Anne-Marie Asselin, marine biologist and founder of the Blue Organization
All levels of government could benefit from this, including municipal government.
The scientists explain that they noticed a clear difference between the two expeditions in the nature of some of the waste found: between 2022 and 2024, for example, plastic utensils gave way to wooden ones. A difference that they attribute to the ban on single-use plastic in Montreal in March 2023.
“This waste continues to end up in the St. Lawrence, but at least the wooden utensils will take one or two years to decompose, rather than hundreds of years,” says Laurence Martel. “This shows that it is possible to slow down plastic pollution.”
“The pollution of the St. Lawrence by microplastics is comparable to the most polluted rivers in the world. We can also wonder to what extent Canada contributes to the continent of plastic in the Pacific Ocean,” says Anne-Marie Asselin. “It is urgent to put in place prevention policies to avoid releasing so much, and at all levels.”
Read our portrait of Anne-Marie Asselin
Check out the Blue Expedition page